linux-kernel - Re: [PATCH] soc: imx: gpcv2: Enable vpumix/dispmix to wait for handshake

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Date:   Mon, 6 Dec 2021 08:45:50 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Adam Ford <aford173@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>
Cc:     linux-arm-kernel@...ts.infradead.org, tharvey@...eworks.com,
        aford@...conembedded.com, Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc: imx: gpcv2: Enable vpumix/dispmix to wait for
 handshake

Hi Lucas,

What's your take on this one?

Shawn

On Sat, Nov 20, 2021 at 01:49:00PM -0600, Adam Ford wrote:
> There is a comment in the code that states the driver needs to
> wait for the handshake, but it's only available when the bus
> has been enabled from the blk-ctrl.  Since both the
> vpumix and dispmix are called from the blk-ctl, it seems
> reasonable to assume the bus is enabled. Add a bool to determine
> which power-domains are able to properly wait for this
> handshake and set the corresping boolean for the two domains
> activated by the blk-ctrl.
> 
> Signed-off-by: Adam Ford <aford173@...il.com>
> 
> diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
> index 7b6dfa33dcb9..a957f7fff968 100644
> --- a/drivers/soc/imx/gpcv2.c
> +++ b/drivers/soc/imx/gpcv2.c
> @@ -204,6 +204,7 @@ struct imx_pgc_domain {
>  	const int voltage;
>  	const bool keep_clocks;
>  	struct device *dev;
> +	bool blkctrl_bus_enabled;
>  };
>  
>  struct imx_pgc_domain_data {
> @@ -282,17 +283,14 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
>  				   domain->bits.hskreq, domain->bits.hskreq);
>  
>  		/*
> -		 * ret = regmap_read_poll_timeout(domain->regmap, GPC_PU_PWRHSK, reg_val,
> -		 *				  (reg_val & domain->bits.hskack), 0,
> -		 *				  USEC_PER_MSEC);
> -		 * Technically we need the commented code to wait handshake. But that needs
> -		 * the BLK-CTL module BUS clk-en bit being set.
> -		 *
> -		 * There is a separate BLK-CTL module and we will have such a driver for it,
> -		 * that driver will set the BUS clk-en bit and handshake will be triggered
> -		 * automatically there. Just add a delay and suppose the handshake finish
> -		 * after that.
> +		 * blkctrl_bus_enabled implies that the GPC is being invoked from a blk-ctrl
> +		 * and not from a peripheral or other GPC power domain.  The blk-ctrl is required
> +		 * to support the handshake.
>  		 */
> +		if (domain->blkctrl_bus_enabled)
> +			ret = regmap_read_poll_timeout(domain->regmap, GPC_PU_PWRHSK, reg_val,
> +							(reg_val & domain->bits.hskack), 0,
> +							USEC_PER_MSEC);
>  	}
>  
>  	/* Disable reset clocks for all devices in the domain */
> @@ -701,6 +699,7 @@ static const struct imx_pgc_domain imx8mm_pgc_domains[] = {
>  		},
>  		.pgc   = BIT(IMX8MM_PGC_VPUMIX),
>  		.keep_clocks = true,
> +		.blkctrl_bus_enabled = true,
>  	},
>  
>  	[IMX8MM_POWER_DOMAIN_VPUG1] = {
> @@ -749,6 +748,7 @@ static const struct imx_pgc_domain imx8mm_pgc_domains[] = {
>  		},
>  		.pgc   = BIT(IMX8MM_PGC_DISPMIX),
>  		.keep_clocks = true,
> +		.blkctrl_bus_enabled = true,
>  	},
>  
>  	[IMX8MM_POWER_DOMAIN_MIPI] = {
> -- 
> 2.32.0
>